The prior art comprises many devices to produce fine mists. The most common of these devices are spray cans that use a chemical propellant to impel a liquid substance through a nozzle. The liquid substance can be water based, alcohol based, or oil based. Less common are pump cans or bottles that utilize mechanical pressure to impel the liquid substance through the nozzle. Vaporizers are available that use heat to expand the liquid, thereby also using pressure to propel it through the nozzle. Finally, ultrasonic devices are used to produce the mist that is impelled through the nozzle.
Fine mist dispensers for oil-based substances must be disposable because the liquid will ultimately clog the nozzle after repeated use. Ultrasonic devices that are not disposable depend upon transport of the liquid substance to a vibrating membrane usually via a saturated wick. The wick can be fabricated from cotton, but other substrates have been used. These ultrasonic devices are best suited to produce an aqueous mist because alcohol evaporates too rapidly to maintain transport of the liquid from the reservoir to the membrane. To be effective, the saturated wick must be in constant contact with the membrane so that there is a liquid film that will be ultrasonically atomized. Thus, these ultrasonic devices are atomizers used principally to produce fine aqueous mists.
Ultrasonic mist dispensers are currently available. They require a small amount of electric current to induce vibration of the membrane at ultrasonic frequencies. A piezoelectric crystal may be used to produce the vibration. Most of these ultrasonic devices are small and portable. Ideally, the liquid to be atomized is distilled water to avoid clogging of the nozzle. Such a liquid substance is used in cool humidifiers. The water vapor thus fills a room, thereby raising the humidity. However, the liquid to be atomized may also contain other chemicals in aqueous solution. These chemicals may include incense, perfumes, airborne inhalation medications, odor neutralizers, and harmless insecticides. Unfortunately, constant production of mists including these chemical substances can be too intense. How often do people go into elevators and smell the annoying odor of lingering perfume. While incense can be useful for aromatherapy, the smell of too much incense can annoy rather than soothe. Too much inhalation medicine in the air could be detrimental to health.
Consumer desires to eliminate noxious odors has fueled a modern industry beginning in the twentieth century. Some bad odors can be eliminated merely by lighting a match or otherwise using fire. In the 1960's, Renuzit® marketed spray cans that filled the surrounding air with fragrances, such as baby powder, to mask odors. These were and are still marketed by that company as air fresheners. Today, Renuzit® sells “cones” containing fragrance gels and “pearls” that both absorb odors and emit pleasing fragrances. Air fresheners are marketed by Glade®, which also markets odor-eliminating candles. Rubbermaid® sells plug-in cartridges that continuously fill a room with a desired fragrance (e.g., citrus scent). Odorklenz® sells products that neutralize some odors such as those from urine. Duluth Trading Co. sells an “odor eliminator” that runs on four C-batteries and uses electrically charged “activated oxygen” in footwear and gloves. This device claims to eliminate odors arising from sweat, mold, mildew, germs, toxins, and pollutants. Hamilton Beach® sells an electronic True Air® Room Odor Eliminator that uses a fan to force room air through three carbon filters, which neutralize the odors, and optionally add fragrances to the air. Biocide Systems™ markets a product that uses chlorine dioxide (ClO2) to neutralize odors. This product, when exposed to the air in a room, neutralizes cigarette smoke odors, skunk odors, cooking odors, and cat urine odors in carpets. The Gonzo® Odor Eliminator uses volcanic minerals to neutralize odors. OdorFree sells ozone generators that neutralize odors. However, free ozone in a room can be toxic to humans. Rocco & Roxie™ Supply Company produces an enzyme spray product to eliminate stains and odors. In 1996, Proctor & Gamble began marketing a product called Febreze®. This product utilizes cyclodextrin (hydroxyl-propyl-beta-cyclodextrin) as its active ingredient. This chemical does not neutralize odors, but rather inhibits the ability for humans to detect the odors. Some sources state that Febreze® also contains zinc chloride, which neutralizes sulfur odors, such as from onions and rotten eggs. However, zinc chloride is not listed as one of the ingredients of Febreze®. All of these products are just examples of products in this crowded industry.
Noxious odors can be divided into three categories, i.e., acidic odors, basic (or alkaline) odors, and neutral odors. Examples of acidic odors include hydrogen sulfide (H2S) [e.g., hard boiled or rotten eggs] and skunk. Examples of alkaline odors include ammonia, urine, and fish smells. Examples of neutral odors include body odors and putrid odors.
Our U.S. Pat. No. 9,993,573 (referenced above and incorporated herein by reference) discloses a non-toxic, water based, natural, herbal extract odor neutralizing substance that can be sprayed into a room or other confined area, which would neutralize acidic, alkaline, and neutral odors. Although, such a product could include fragrances, the purpose of such a product would be to neutralize the odor rather than to mask the odor.
Our U.S. patent application Ser. No. 15/400,964 (referenced above and incorporated herein by reference) discloses an ultrasonic dispenser that produces a cool, fine aqueous mist. That mist may consist only of water, or it may comprise other substances intended for introduction into the surrounding air. It comprises an electronic cap capable of producing the mist ultrasonically, which sits atop a reservoir filled with liquid. The cap is connected to a programmable device, which in turn is connected to a power source. When the reservoir is filled with the aqueous solution disclosed in our U.S. Pat. No. 9,993,573, the dispenser is able to continuously generate a mist into a closed area that will not mask but will neutralize all types of odors. This aqueous deodorizing chemical solution is but an example of what can be used as an odor neutralizer in this type of device.
However, our dispenser was designed to be small enough to be used by consumers in their homes. Generally, a water-based dispenser effuses a mist for a short duration, usually six to eight hours. Even if the unit were larger with a much larger reservoir, dispensation of the deodorizing mist would take place over a maximum duration of 24 to 28 hours. The reservoir would need to be refilled regularly.
For release into a fixed volume and for a finite time, all dispenser systems do this. However, there is nothing on the market that will allow the emissions to last for a long time period (e.g., one month).
Another problem stems from the fact that a water-based mist is wet. Though it is sprayed into the air, some of it condenses on surfaces leaving a wet film that is somewhat difficult to wipe away.
There is a need for a device that would release a dry fog of deodorizing material into the air of a closed area for a long time. The need extends beyond ordinary consumer applications. It would be desirable for such a deodorizing substance to be able to propagate through air conditioning systems into large areas. It would also be desirable not to require refilling the liquid in the reservoir for a period less than one month.
The problem of the wetness is solved by releasing a vapor (or dry fog) into the air at room temperature rather than a mist. If a droplet particle size is greater than or equal to ten microns 10μ), it is a mist, and the particles fall like rain. When the particle size is less than or equal to five microns 5μ), such a vaporous substance is dry. It does not condense. Further, the problem of a short duty cycle is solved by using a large industrial sized reservoir.
Moreover, the smaller the particle size, the greater the deodorizing effect. It is a surface area effect rather than a volume effect. The smaller the particle size, the greater the number of particles, thereby causing the total surface area of the aqueous particles to be higher. The greater the surface area, the more solute can interact chemically with odor causing chemicals. Therefore, the greater the number of particles in the air, the higher the probability of odor neutralization. Thus, with smaller particles, there is a greater effectiveness of deodorization per unit weight of aqueous solution in the air.